Preparation of mixed dicarboxylic acid esters of polyhydroxy compounds and monohydroxy alcohols



time Aug. 22,1939

PREPARATION on non) zsrrsns or rommssunmono:

our a. Hahn e Charles R. rims-ms..-

tar, N. Y., are, bye asslgnmen Eastman Kodak Company, ester, N. 2., acorporation of New Jersey No Drawing.

Application December 4, 1935, Serial No. 52. 878

3 Claims. (Cl. 260-475) I This invention relates to the mixed dicarbox-'ylic acid esters of polybydroxy compounds and monohydroxy alcohols,such as for example, ethyl ene glycoldiethyl diphthalate and theircomposi-tions with cellulose-esters. The present. application is acontinuation-in-part of our copending application, Serial No. 632,560,filed Septemberv 1932 which has matured into Patent #2023,- 8

Our invention involves the preparation of these mixed esters by reactingupon a dicarboxvlic acid ester of a polybasic compound in which one oithecarboxyl groups of the acid is free and unestel'ifled with amonohydroxy alcohol to form I: an ester. containing both alkyl groupsand groups derived from the polybasic compounds and the products formedthereby. Our invention also involves' the plasticizing of organic acidesters of cellulose with these mixed dicarboxylic acid esters.Compositions of matter comprising cellulose esters may be employed toproduce valuable products of various kinds, such for example, assheeting, molded products, rods, tubes, artificial leather, etc. 7 Asplasticizers for cellulose deriva- 25 tlves these mixed dicarboxylicacid esters are unique in that they are, as a. class, highly compatiblewith cellulose derivatives and, due to their high molecular weight, havevery low vapor pres-. sures. They are entirely insoluble in water, mak-30 ing them useful in compositions where moisture.

resistance is an important factor.

We have found that the acid dicarboxyllc acid esters of polyhydroxycompounds prepared according to the process described inzour Patent No.2,023,485, may be caused to react with a monohydroxy alcohol,- such asmethyl or ethyl alcohols therebyesterifyingthe remaining carboxyl group.We have found that dicarboxylic acid esters so prepared which containboth monohydroxy al-- 4o cohol and a polybaslc alcohol substituent maybe incorporated with a cellulose ester to form a composition possessinga good and permanent fiexlbilitywhich is, suitable for employment in:

any connection in whichplasticized cellulose cs- 45 ters are employed atthe present time.

The acid dicarboxylic acid esters of polyhydroxy compounds which areemployed as the starting material in the process of the presentinvention 632,560 now Patent No. 2,023,485, which is a parent of thepresent application.

The acid dicarboxylic acid ester of a polyhydroxy alcohol is esterifiedby reacting" upon the compound with a monohydroxy alcohol by treat- 5ing it with an excess of the alcohol preferably in anhydrous form in thepresence of a catalyst; for example, about pounds of' ethylene glycolacid diphthalate was dissolved in 60 to 80 pounds of anhydrous ethylalcohol into which was introduced about 1% of dry I-ICl gas. The wholewas allowed to stand at about C. for approximately 24 hours at the endof which time the HCl and alcohol were distilled ofi. The ethyleneglycoldiethyl diphthalate'formed was refined by dissolving it in ether,washingthe ether solution with aqueous sodium carbonate and drying itwith caicium chloride. The ether was themdistllled oil? and the productobtained as residue.

This process is susceptible of use with any of the compounds which havebeen described as suitable in the present or the parent case.

Although due to their commonness, the us of methyl or ethyl alcohol isordinarily preferred for esterifying the acid dicarboxylic esters,nevertheless, other monohydroxy alcohols may be employed for thispurpose. Any of the acid dicarboxylic compounds described in ourcopending application will be found to be susceptible to fur-- theresteriflcation ,by the monohydroxy alcohols in accordance with thepresent application. Substituted alcohols such as B. methoxyethylalcohol may also be used. I

These dicarboxylic acid esters in which the hydrogen of one carboxylgroup is replaced by a polyhydroxy compoundgroup and the hydrogen of theother carboxyl by a monohydroxy alcohol group are eminently suited forplasticlzing cellu-v lose derivatives with which'they are compatible.For example, an acetone-soluble cellulose acetate containing 10% ofethylene glycol dimethyl diphthalate when coated out from its solutionin the form of a sheet exhibited a flexibility of 6 folds when tested ona Schopper fold tester. This sheet was subjected to heat of 65 for morethan 135 days before it became brittle in contrast to onlya -day periodto produce brittleness in a sheet of non-plasticized cellulose acetate.These plasticizers are also useful in the case of cellulose nitrate andcellulose others. Ethylene glycol dimethyl diphthalate unlike some ofthe commonly employed plasticizers, is compatible in all proportionswith these derivatives oii cellulose.

Some examples of the use of these plasticizing compounds with organicesters for various purposes follow. Theseexamples are to be understoodas being illustrative and not for the purpose of limiting our invention.

(1) Sheeting or jilm.-100 parts of cellulose acetate having an acetylcontent of 40% and a viscosity 01' 2.000 centipoises was dissolved in350 parts of acetone and 15 parts of hydroquinone diethyl diphthalatewas added to the solution. After the solution became homogeneous, it wascoated out on to a smooth shiny surface. A flexible, transparent sheetresulted. For certain purpwes it is desirable to increase the plasticityof the sheeting in which case the amount of pinsticizer should beincreased to 25% or 30% of the weight of the acetate.

(2) Molding compounds.--To 100 parts of finely lmlverized celluloseacetate is added 20-50 parts of ethylene glycol dimethyl diphthalate asthe plasticizer whereupon the powder may be molded by any method wellknown in the art, such as by heating at 140-160 C. at a pressure of2500-4000 lbs. per square inch for 2-5 minutes. If a product having ahard surface is desired, 20 parts -of the plasticizer would besufllcient while in cases where higher plasticity is preferred up to 50parts may be employed.

(3) Paste-100 parts of cellulose acetate is added to a mixture of 34parts of ethylene glycol diethyl disuccinate, 13 parts of ethyl alcoholand 79 parts or acetone. The mixture may then be worked up to the pointof homogeneity and the paste thus formed may be worked on rolls andextruded for the manufacturing of rods, tubes, etc.

(4) Artificial leather.-75-80 parts of pigmented glycerol trimethyltriphthalate may be added to a solution of 100 parts of celluloseacetatepropionate (containing 20% propionyl and 25% acetyl) in a mixtureof 80% ethylene chloride 20% methyl alcohol. This solution or dope maythen be coated onto cloth which may then be subjected to warmcalendering. 3 or 4 coats of the dope may be applied to give the productthe desired thickness. It may then be given an embossing treatment toobtain a product physically similar to leather.

It is to be understood that these plasticizers may. be employedinterchangeably in various connections. For example. the glyceroltrimethyl trlphthalate might be employed in the paste composition or forthat matter in the molding or the sheeting compositions if desired.

Some of the esters which we have prepared and have found suitable asplasticizers for cellulose derivatives particularly the organic acidesters of cellulose are:

Glycerol trimethyl triphthalate Ethylene glycol dimethyl diphthalateHydroquinone diethyl diphthalate Glycerol trimethyl trisuccinateEthylene glycol diethyl disuccinate Hydroquinone dimethyl disuccinateInstead of preparing thesecompounds as disclosed above they may also beprepared by reacting upon an acid monobasic alcohol ester 01' adicarboxylic acid with a polyhydroxy compound. For instance, if an ethylacid phthalate, the preparation of which is disclosed in U. S. PatentNo. 1,704,306 of Stinehfleld, is employed as the starting material andthis ester is reacted upon a polyhydroxy compound such as ethyleneglycol in the presence of a suitable catalyst, an ethylene glycoldiethyl diphthalate would be formed.

The mixed dicarboxylic acid esters of polyhydroxy compounds andmonohydroxy alcohols may be represented structurally as follows:

Ethylene glycol diethyl diphthalate C IR Glycerol trimethyl triphthaleteClix-(Fi iint.

com

The term polyhydroxy compound as employed herein is to be understood asreferring to compounds such as the dior tri-hydroxy alcohol and thepolyhydroxy phenols. This term does not include the group oi'compoundsknown as the saccharides which group includes sugars, starch, dextrin,cellulose, cellobiose and their immediate derivatives.

We claim as our invention:

1. The process of preparing a mixed ester of a dicarboxyllc acid whichcomprises reacting upon a non-saccharlde polyhydmxy compound with theanhydride of the dicarboxylic acid at approximately C. in the presenceof at least an equivalent amount of a tertiary organic base, separatingthe resulting product from the reaction mixture by precipitating indilute acid and then reacting thereupon with a lower aliphaticmonohydroxy alcohol in the presence of a suitable catalyst.

2.. The process of preparing a mixed ester of phthalic acid whichcomprises reacting upon a non-saccharide polyhydrow compound withphthalic anhydrlde at approximately 100 C. in the presence of at leastan equivalent amount of a tertiary organic base, separating theresulting product from the reaction mixture by precipitating in diluteaqueous acid and then reacting thereupon with a lower aliphaticmonohydroxy alcohol in the presence of a suitable catalyst.

3. The process of preparing a mixed ester of a dicarboxylic acid whichcomprises reacting upon ethylene glycol with a. dicarboxylic acidanhydride at approximately 100 C. in the presence of at least anequivalent amount of a tertiary organfc base, separating the resultingproduct from the reaction mixture by precipitating in dilute aqueousacid and then reacting thereupon with a lower aliphatic monohydroxyalcohol in the presence of a suitable catalyst.

CARL J. MALM. CHARLES R. FORDYCE.

